/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [https://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package org.neo4j.internal.batchimport.staging;

import org.neo4j.batchimport.api.Monitor;
import org.neo4j.internal.helpers.progress.ProgressMonitorFactory;

/**
 * Takes multiple 0..100% progresses and aggregates those into a simple progress into {@link Monitor#percentageCompleted(int)}
 * where each
 */
class WeightedExternalProgressReporter implements AutoCloseable {
    private final Monitor monitor;

    private int overallPercentage;
    private double weight;

    WeightedExternalProgressReporter(Monitor monitor) {
        this.monitor = monitor;
    }

    ProgressMonitorFactory.IndicatorListener next(double weight) {
        this.overallPercentage += 100 * this.weight;
        this.weight = weight;
        return new ProgressMonitorFactory.PercentageIndicatorListener(1) {
            private int lastLocalPercentage;

            @Override
            public void percentage(int percentage) {
                int localWeightedPercentage = (int) (percentage * weight);
                if (localWeightedPercentage > lastLocalPercentage) {
                    monitor.percentageCompleted(overallPercentage + localWeightedPercentage);
                    lastLocalPercentage = localWeightedPercentage;
                }
            }
        };
    }

    @Override
    public void close() {
        if (overallPercentage < 100) {
            monitor.percentageCompleted(100);
            overallPercentage = 100;
        }
    }
}
